Dodge Senior, Random fuel starvation

[gundog99]

Over the last three years my Dodge Senior has suffered from what I can best describe as random fuel starvation. To minimise it I have had to cut down my speed to about 35 MPH . When the engine is hot I might have driven for about six miles when the engine starts to cut out then run, cut out , run, ect ect, in quick succession, sometimes it will then stops, after a minute I can restart it and it will run again, the problem  may  or not.be repeated.

This year I am chemically cleaning out the cooling system , last year I overhold  the Vacuum tank, striped the carburetor, rerouted some of the pipework ,replaced the coil and condenser. I also fitted a newly restored head, in spite of all this the problem persists. 

I have replaced a very old inline  fuel filter that is between the tank and the vacuum tank. Is there enough vacuum to pull the fuel through a modern filter or should I be fitting something else?  

Will rust in the tank stop the flow of fuel?

Or is the problem just moden fuel ?

[RichBad]

One thing worth checking is the valve clearances.  Someone who knows far better than me mentioned that on the fours, if they are too tight it can give symptoms similar to fuel starvation particularly when hot/under load.  He mentioned that modern fuels can exacerbate this as the exhaust valves get hotter and can close up the clearance if too small.

 

not sure if it is the same for the sixes?

[nearchoclatetown]

Sounds a lot like a condenser.

[Bullfrog_eng]

I agree it MAY be a condenser. I had been playing with cars for 40 years before I encountered a crook condenser, actually two in quick succession. The first one nearly drove me round the bend over several months, seemed just like fuel starvation, but very intermittent. I had the carbi off so many times, I considered putting wing nuts on it!! Mate told me to change the condenser and that fixed it straight away. Easy to replace and won't cost much to prove one way or the other.

[gundog99]

Thank you everyone. The Valves were set up with allowance for them being cold, when the head and carburetor was off, much easier to set up when the car is on a ramp and they are at eye level.  Any idea what the settings should be for today's fuel? 

I have a new Bosch condenser which I will fit.

[Ron Lawson]

I hope you get it sorted out Anthony 

[Flivverking]

I'm just passing through and caught your delema.

My money is on a pure fuel starvation..Many a modern car has suffered the same symptoms which most often is clogged fuel filters..

The car quits after a few miles but  will restart after is sits a bit.(Sometimes a near dead fuel tank mounted fuel pump can do the same kinda thing)  It repeats the pattern and trouble often can vanishfor awhile ,then start up again.

Replace or ditch the modern fuel filter and also use a plain glass bowl sediment filter after the vaccum tank outlet to carb.We put a heavy duty glass filter in the frame rails hidden on some cars but kept repair stuff in the car incase the glass broke.

And alway have a glass sediment bowl between the gravity VTank and carb.

 

Next focus on the fuel  feed vacuum tank.Again!

 

We had a 29 essex that did the same sorta thing your DB is doing  back in 1970s..It would randomly starve and stop.We thought vacuum tank float wasn't working well so we carlessly would bang on the gavity vacuum tank ,prime it and go on..Somestimes good for a day or play hop scotch all day feeding the tank.

 

Actual problem.

1. Dirty fuel tank..no rust particals but fine rust silt .

2.The vacuum tank we used on the Essex was a typical Stewart Warner and it had a filter screen on top(under a big brass nut with fuel feed inlet elbow through the nut) the screen was packed solid with micro rust silt .It was porous enough to let the fuel be sucked through when dry and suction would fill the Vtank and we go.

After a while the silt would pack down wet.not letting fuel though and the Vtank ran dry..STOPIng  car to a hault.

We'd refill the vacuum  tank, bang it with a rubber mallet(loosing up the silt not stuck float) and we be good for a while or not..

Did that for a year.

Many a Chinese fire drill we did at stop lights.

We check that screen by accident and found the crud finally..We didn't know the screen was there.

I must say It was an exciting discovery!

S.O.A.B!

CHECK THAT SCREEN.

 

Now If you can't get long term speed or car stumbles and seems to miss during these episodes ,the vacumm tank may just barley be suppling enough fuel in a different way. .Secretly it may never really be filling to capacity  for enough carb. fuel supply..

 

We had a '23 original Durant touring car that the Vtank float can's lower flapper valve was stuck closed from the inside with caked with crusty varnish..Just a slight slit to let fuel drain slowly from the top to bottom can then into the carb bowl .Just enough to get driving but in short order the carb bowl would empty..By time you check the fuel line for flow out of the vacuum tank carb. line ,the upper float can has finally empty into the lower tank and the flow out of the line appears great for the 2 seconds you test flow.

We cleaned that flapper valve (which is there as to not draw fuel back up and hold vacuum when the Vtank is sucking from the rear gas tank) and we never had any more trouble. 

Another revelation milestone.

 

 

Check all points of filter and fuel flow.

Again!

 

I forget the Dodge updraft carbs but many carbs have inlet fuel screens ..Our Essex did..but all the crap was caught at the Vacuum tank.

If vacuum tank is the sorce ,please don't turn to an electric fuel pump.Sort it out.

You will be glad you did.

 

The Vacuum Gravity feed fuel pump is an extremely dependable unit.Most were abandoned for simple broken foat springs ,dirt or leaking top gaskets.after years and years of trouble free service.

 

The old time restorers would ask us kids."what separates the real men restorers  from the wannabee boy restoreres? The gravity vacuum fuel pump" was the anwser.

 

Good luck.

 

 

[old car fan]

Fliv,you just said everything that needs said.spot on we restore and supply parts,rebuild kits.OUR first tank is still on the car,20 years,never been touched.

Edited May 19, 2020 by old car fan (see edit history)

[Ron Lawson]

Anthony, Does your Vac tank have one single outlet in the bottom or two If you have a one hole version I can send you a sediment bowl to suit 

[Fossil]

Something else to consider.  Ignition coils when starting to fail will act just like your symptoms.  You'll be driving down the road and the engine will start cutting out and then die.  You coast or push the car to the side of the road and shortly after it will start again.  Drive a ways and the same thing happens again. 

When the coil starts to heat up an open in the circuit occurs.  Shortly after the engine dies the coil cools and the open closes again.  I'm not saying this is your problem but it is another thing to check if the problem persists.  Someone put me onto this years ago when I was having your problem and a new coil was the cure. 

[gundog99]

I had a look at the inline fuel filter ,There was a large air bubble ,I have managed to deduce it by 50% . The engine was ticking over when I took the photographs. When the vacuum pump kicked  in the fuel, before going through the  filter element it frothed up  and the engine momentary seems to lose power .

I think the filter I part of problem together with sludge in the tank. The vacuum tank  will need to be looked at again,I was very careful to clean all the parts when I stripped it down last year. Some one ,not me, put the fitting the wrong way round in the past and cannot be changed without damaging the tank.

Edited May 20, 2020 by gundog99 (see edit history)

[hwellens]

I think the "bubble" is there when the carburetor is full and the gas seeks the level of the gas lines.

[Ron Lawson]

Your picture answers my question The sediment bowel that I have won't fit 

 

[gundog99]

Following the excellent advice everyone has given me on this thread. I undid all the fittings on the vacuum tank top,  founded and removed the filter screen. I didn't think it was the original one. It had been pushed hard into the bottom of the casting, past the three luds that I assume the original rests on, there was a tiny bit of dirt in it but enough with the incorrectly fitted screen to restrict the flow of petrol.I have now pushed it to the bottom of the brass union allowing the fuel to pass through a much increased area of the screen . There is now a lot more fuel going through the inline filter at greater pressure and for a longer time.

A long test drive on Friday, fingers crossed !

Edited May 20, 2020 by gundog99 (see edit history)

[Ron Lawson]

Good luck Anthony I hope you have fixed the problem These little njggly buggers can be very frustrating 

 

[Fossil]

Hope it runs good for you. Enjoy the drive. 

[gundog99]

My test run on Friday did not go well! I replaced my Indian made coil with my spare  US manufactured one and a new condenser (Mexican ), vertically not horizontally , as I had fitted the previous one , I hadn't realized this is the correct way round for most coils . 

The Dodge is now running perfectly ,well almost for a 93 year old car. 

Edited May 24, 2020 by gundog99 (see edit history)

[Fossil]

Have run into coil problems before and it is surprising how the symptoms can appear fuel related.

Congratulations on resolving your problem.